1. Field of the Invention
The present invention relates to an apparatus and a method of loading a lens-fitted photo film unit with photo film. More particularly the present invention relates to an improvement of a photo film loading apparatus and a method in which the loading process is highly automated.
2. Description of the Related Art
Known lens-fitted photo film units (hereinafter referred to simply as photo film units) are disclosed in U.S. Pat. Nos. 4,884,087 and 4,972,649 (both corresponding to Japanese Patent Publication No. 2-32615), and are now available commercially, e.g., under the trade name "Fujicolor Quick Snap" (manufactured by Fuji Photo Film Co., Ltd.). Such photo film units are a single-use camera pre-loaded with a photo filmstrip (hereinafter referred to as photo film) in a cassette of a 135-type, as defined by ISO 1007, 1979 version, and incorporate a taking lens, a shutter device, and other mechanisms required for photography. The photo film unit has a mechanism for winding the photo film, but lacks a mechanism of feeding the film in a direction reverse to the winding direction, to reduce the cost of production. A user who has purchased the photo film unit winds the photo film frame by frame back into the cassette after each exposure. In production of the photo film unit, a loading apparatus draws the photo film out of a cassette shell, in a darkroom, in the form of a roll, and loads a photo film chamber with the roll of the photo film, while loading a cassette containing chamber with the cassette shell.
To form the roll from the drawn photo film, the loading apparatus has a station for winding the photo film. The roll forming station has a shaft device on which a leader of the photo film is secured. Although the roll is formed in the darkroom, a manual operation in an illuminated room is conventionally required before forming the roll. With the cassette shell set in the roll forming station, the manual operation pulls a predetermined length of the leader out of the cassette shell, and secures the leader of the photo film on the shaft device. The conventional operation of loading of the photo film requires a great deal of time. The length of pulling the leader from the cassette shell tends to change due to changes in the manual operation. A pulled portion on the leader is exposed to ambient light, and fogged. Accordingly a length of the photo film usable for the exposures is not constant. An available maximum number of exposures cannot exceed a standard number of which exposures could be safely taken without being fogged.